Scale coloration change following water absorption in the beetle Hoplia coerulea (Coleoptera).

The blue scales on the cuticle of the male beetle Hoplia coerulea can absorb water, with the consequence that these scales, which have been shown to be responsible for the beetle's bright blue coloration, reversibly turn to emerald green with increasing water contents. Optical measurements are shown, by analytic photonic-crystal models, to be compatible with the full filling of the scales structures with water. The natural mechanism shows the way to produce a very efficient hygrochromic material: a medium which significantly changes color when its water contents are modified.

[1]  Igerna B. J. Sollas,et al.  On the identification of chitin by its physical constants , 1907 .

[2]  Alain Cornet,et al.  Spectral filtering of visible light by the cuticle of metallic woodboring beetles and microfabrication of a matching bioinspired material. , 2006, Physical review. E, Statistical, nonlinear, and soft matter physics.

[3]  Jean-Pol Vigneron,et al.  Diffractive hygrochromic effect in the cuticle of the hercules beetle Dynastes hercules , 2008 .

[4]  J. Putaux,et al.  Structural data on the intra-crystalline swelling of β-chitin , 2000 .

[5]  W. Stark,et al.  Highly sensitive optical detection of humidity on polymer/metal nanoparticle hybrid films. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[6]  Brand Fortner,et al.  Number by colors - a guide to using color to understand technical data , 1996 .

[7]  Jean-Pol Vigneron,et al.  Structurally tuned iridescent surfaces inspired by nature , 2008 .

[8]  Serge Berthier,et al.  Determination of the cuticle index of the scales of the iridescent butterfly Morpho menelaus , 2003 .

[9]  Jean-Pol Vigneron,et al.  Natural layer-by-layer photonic structure in the squamae of Hoplia coerulea (Coleoptera). , 2005 .

[10]  S. Brush.  History of the Lenz-Ising Model , 1967 .

[11]  Brand Fortner,et al.  Number by Colors , 1997, Springer New York.

[12]  J. Vigneron,et al.  Color-selecting reflectors inspired from biological periodic multilayer structures. , 2006, Optics express.

[13]  A. Parker,et al.  Aphrodite's iridescence , 2001 .

[14]  Olivier Deparis,et al.  Switchable reflector in the Panamanian tortoise beetle Charidotella egregia (Chrysomelidae: Cassidinae). , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[15]  Jean Pol Vigneron,et al.  Variation of a photonic crystal color with the Miller indices of the exposed surface , 2006, SPIE OPTO.

[16]  Xiaodong Wang,et al.  Fabrication and properties of a porous chitin/chitosan conduit for nerve regeneration , 2004, Biotechnology Letters.

[17]  N. F. Hadley.  Wax Secretion and Color Phases of the Desert Tenebrionid Beetle Cryptoglossa verrucosa (LeConte) , 1979, Science.

[18]  E. Thomas,et al.  Broad-wavelength-range chemically tunable block-copolymer photonic gels. , 2007, Nature materials.